1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor and, more particularly, to a multilayer ceramic capacitor capable of preventing a crack and a breakdown (i.e., dielectric break) due to a thermal impact while stably securing capacitance.
2. Description of the Related Art
In general, a multilayer ceramic capacitor includes a plurality of ceramic dielectric sheets and inner electrodes interleaved with the plurality of ceramic dielectric sheets. Because the multilayer ceramic capacitor can implement a high capacitance for its small size and can be easily mounted on a substrate, it is commonly used as a capacitive component for various electronic devices.
Recently, as electronic products (i.e., home appliances, etc.) have become more compact and multi-functional, chip components have also tended to become compact and highly functional. Following this trend, a multilayer ceramic capacitor is required to be smaller than ever before, but to have a high capacity, and at present, a multilayer ceramic capacitor having five hundred or more dielectric layers, each with a thickness of 2 um or less stacked therein, is being fabricated.
In this respect, however, because the ceramic dielectric layers are extremely thin and highly stacked, the volume ratio of the inner electrode layers increases, causing a crack or a breakdown (i.e., dielectric break) in the ceramic laminated body due to a thermal impact applied in the process of mounting them on a circuit board by firing, reflow soldering, or the like.
In detail, a crack is generated as stress caused by the difference of thermal expansion coefficients between a material forming the ceramic layers and a material forming the inner electrode layers acts on the ceramic laminated body, and in particular, both edges of the upper and lower portions of the multilayer ceramic capacitor are mostly cracked.
In addition, stress is also generated at the uppermost and lowermost portions of the dielectric layers due to a thermal change, and in this case, when voltage is applied, a breakdown of the dielectric layers may be generated.